Example vertical cavity surface emitting lasers (VCSELs) include a mesa structure disposed on a substrate, the mesa structure including a first reflector, a second reflector defining at least one diameter, and an active cavity material structure disposed between the first and second reflectors; and a second contact layer disposed at least in part on top of the mesa structure and defining a physical emission aperture having a physical emission aperture diameter. The ratio of the physical emission aperture diameter to the at least one diameter is greater than or approximately 0.172 and/or the ratio of the physical emission aperture diameter to the at least one diameter is less than or approximately 0.36. An example VCSEL includes a substrate; a buffer layer disposed on a portion of the substrate; and an emission structure disposed on the buffer layer.